Coil-oscillator vibration unit for rail workhead

ABSTRACT

A rail maintenance vehicle includes a frame, a workhead, and a vibrating unit. The frame includes wheels that travel along rails. The vibrating unit is coupled to the workhead and includes a rotor, a stator, a first rotor coil coupled to the rotor and a first stator coil coupled to the stator.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation application of U.S. patentapplication Ser. No. 15/211,769 filed on Jul. 15, 2016 which claimspriority to U.S. Provisional App. Ser. No. 62/193,375, filed on Jul. 16,2015, each of which is hereby incorporated by reference in theirentirety.

BACKGROUND

Generally, railroad tracks include a pair of parallel rails coupled to aseries of laterally extending ties (or sleepers). Ties may be made fromconcrete or wood. Each tie is coupled to the rails by metal tie platesand/or spring clips. The ties are disposed on a ballast bed. The ballastmay be a hard particulate material, such as gravel. The ballast filledspace between the ties is called a crib.

Although appearing rigid, rails are flexible members that can bend anddistort, for example under the load of trains passing over. The ballastacts like a cushion absorbing some of the shock. Ballast can also helpkeep the rail level and allow moisture and rain water to drain away.

During installation and maintenance, ballast may be “tamped” to maintainproper position of the ties. Tamping involves agitating the ballast toallow the particles to re-position, and compact it under the tie.Tampers may also track stabilizer workheads for applying pressure to atrack structure.

A tamping device includes one or more workheads mounted on a motorizedvehicle that travels on the rails. A workhead may include a pair ofelongated, vertically extending tools structured to move togethervertically and horizontally in a pincer-like motion. The workhead mayhave two sets of tools spaced so that each tool may be disposed onopposite lateral sides of a rail. The workhead may further include avibration device configured to rapidly vibrate the tools.

The vibration device is generally a hydraulic actuator, which mayrequire many components to drive such as hoses, hydraulic circuit pumps,tanks and filters. Moving parts in the hydraulic systems may wear andfail. The hydraulic systems may also leak requiring work stoppage formaintenance. A vibration device of greater efficiency and reliabilitywould be advantageous.

BRIEF SUMMARY

In an embodiment, a rail maintenance vehicle includes a frame, aworkhead, and a vibrating unit. The frame includes wheels that travelalong rails. The vibrating unit is coupled to the workhead and includesa rotor, a stator, a first rotor coil coupled to the rotor and a firststator coil coupled to the stator.

In another embodiment, a vibration unit for a rail vehicle includes arotor, a stator, a first rotor coil, a second rotor coil, a first statorcoil, a second stator coil and a controller. The first rotor coil iscoupled to the rotor. The second rotor coil is coupled to the rotor. Thefirst stator coil is coupled to the stator and proximal to the firstrotor coil. The second stator coil is coupled to the stator and proximalto the second rotor coil. The controller is operable to alternatinglycause the first rotor coil and the first stator coil to have a firststate and the second rotor col and the second stator coil to have asecond state.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a tamping machine rail vehicle where a coil-oscillatorvibrator unit can be implemented, according to an example embodiment.

FIG. 2 shows a front view of a tamping workhead assembly.

FIG. 3 shows a top view of an electrically driven vibrating unit.

FIG. 4 shows a perspective view of an electrically driven vibratingunit.

FIG. 5 shows a circuit diagram that may drive a coil-oscillator.

FIG. 6 shows electrical waveforms of the circuit of FIG. 5.

DETAILED DESCRIPTION

Embodiments of a coil-oscillator vibrator unit and related methods forapplying vibration to a work head in a rail vehicle are described. It isto be understood, however, that the following explanation is merelyexemplary in describing the devices and methods of the presentdisclosure. Accordingly, any number of reasonable and foreseeablemodifications, changes, and/or substitutions are contemplated withoutdeparting from the spirit and scope of the present disclosure.

In an embodiment, the coil-oscillator vibrator unit is employed in atamping machine rail vehicle, as illustrated in FIGS. 1 and 2. FIG. 1shows a tamping vehicle 100 that includes a frame assembly 102, apropulsion device 104, a tamping device 106, and a cabin 108. Frameassembly 102 includes a plurality of rigid frame members and a pluralityof wheels 109 that are configured to travel on the pair of rails 101.Tamping vehicle 100 travels across a pair of rails 101, disposed over aseries of rail ties 103. The rails 101 and series of ties 103 aredisposed over a bed of ballast. The propulsion system 104 is configuredto move tamping vehicle 100. The tamping device 106 is configured totamp rail ties 103.

The tamping device 106 may include multiple workheads. In the side viewof FIG. 1, one workhead can be viewed while another workhead is alsoincluded at an opposite side corresponding with the other rail. Anynumber of workheads (2, 4, etc) may be included. The tamping device 106includes paddles 110 that are lowered into the ballast. The paddles 110are vibrated by vibrators 114. The paddles 110 may be actuated byactuators 120, which may be hydraulic, to squeeze the paddles around therail ties. The tamping device 106 is coupled to the frame assembly 102via a subframe 116 and an actuator 118. The actuator 118 is preferably ahydraulic actuator and is operable to lower the tamping device 106 suchthat the paddles 110 are inserted into the ballast where the squeezingand vibration action tamps the ballast. The vibrators 114 may couple toor be integrated with the actuators 120. In a work cycle, the tampingvehicle 100 advances to position the tamping device 106 over a tie. Theactuator 118 is actuated to lower the tamping device 106 to carry outthe tamping of the ballast by actuation of the vibrators 114. Then, theactuator 118 is actuated to raise (and in some cases stow) the tampingdevice 106 for travel to the next tie.

FIG. 3 shows a top view of an electrically driven vibrating unit. FIG. 4shows a perspective view of an electrically driven vibrating unit. Withreference to FIGS. 3 and 4, the vibrator 114 includes a rotor 202 and astator 204. The pole faces 206 on the rotor are convex and complementaryto the concave pole faces 208 on the stator. The complementaryconvex-concave profiles allow a constant air gap to be maintainedbetween their surfaces. A constant air gap provides for more consistentand reliable coupling between rotor and the stator as these faces act asthe pole faces of the magnet.

In a resting position, the axis of rotation of the rotor may be slightlyoffset from the center axis of the coils to allow movement to start in apredictable direction by operation of the strength of the force vectorsgenerated by the flux in the coils. The offset allows for predictablestartup and operation while reducing the complexity of the controller asit may not be necessary to know an absolute position of the rotor whilestill permitting predictable startup and operation of the vibrator. Theoffset may be provided, for example, a central axis of each statorportion may form an angle with a central axis of the rotor. Both statorportions may be offset to the same side of the central axis of therotor.

The rotor 202 may be wedge or hour glass shaped to proved greater massdistal from the center shaft 203. These larger masses may increase theenergy in the oscillations. In an embodiment, the oscillations may beabout 2 degrees (less than the resting offset). The energy needed totamp ballast is very high. Thus, the geometry of the rotor isparticularly advantageous in the rail maintenance context to provide acompact but powerful vibrator.

The rotor 202 and the stator 204 may each include two coils: a firstrotor coil 220, a second rotor coil 222, a first stator coil 224, and asecond stator coil 226. The coils may be respectively wound around anexterior of the rotor and stator. The coils may also be wound in anannular opening within the rotor and/or stator such that a diameter ofthe coils are substantially uniform. A partial rotation can be achievedby energizing coils on the rotor and stator with opposing fields.Reversal of the flux at a partial rotation can be achieved to deliver atorque oscillation.

The rotor 202 may achieve clockwise movement when coils 224 and 220 havethe same polarity and coils 222 and 226 have reverse polarity. Theoffset of the rotor, for example five degrees, initiates a torque due toslip. In the view of FIG. 3, applying the same polarity to the coils 220and 224 causes a force at the coil 220 in the right hand direction.Because the rotor is mounted on a pivot (e.g., a shaft 203), this causesan angular displacement. Conversely, the rotor 202 may achievecounter-clockwise movement when coils 220 and 224 have reverse polarityand coils 222 and 226 have the same polarity. Optionally, the coils maybe de-energized in one phase of the oscillation. For example, where thecoils are described above as having the reverse polarity, the coils mayinstead be de-energized and the oscillatory movement provided by thecoils alternatingly having the same polarity. As another example, wherethe coils are described above as having the same polarity polarity, thecoils may instead be de-energized and the oscillatory movement providedby the coils alternatingly having reverse polarity.

The coils 224 and 220 may be coupled by a flexible conductor. The coils226 and 222 may also be coupled by a flexible conductor. Theelectrically coupled coils 224 and 220 may be coupled to a controllervia conductors 230 a and 230 b. The electrically coupled coils 226 and222 may be coupled to a controller via conductors 232 a and 232 b.

The oscillatory displacement of the rotor 202 relative to the stator 204may be small. In an embodiment, the rotor 202 oscillates 2 degrees. Aflexible conductor can therefore couple to the coils 220 and 222 of therotor to the coils 224 and 226 of the stator with limited mechanicalstrain. Other than conductors for the coils and the pivot shaft 203, therotor 202 may be free to rotate and does not require any further contactto the stator. For example, this may eliminate brushes, commutators, andother mechanical couplings that wear providing improved longevity of thevibrator. The flexible conductors and conductors 230 b and 232 b do notsignificantly affect the ability of the rotor 202 to oscillate freelyabout the shaft 203. The stator 204, and thereby also the vibrator 114may be secured to a machine via the fixed mount 240. As the rotor 202has low friction with the stator 204, the vibrator 114 may be veryefficient and have a long useful life.

FIG. 5 shows an exemplary dual half-wave rectifier circuit 300 that canbe used to control a push-pull system that alternatively repel and pullcausing the rotor 202 to oscillate and give a torque on a shaft 203. Inanother example, the circuit 300 may be used to control an alternatingpush-opposing push or alternating pull-opposing pull to provide theoscillations. The dual half wave rectification circuit may split theinput current into two half wave forms that are out of phase causingalternating repelling and attracting forces that in turn cause the rotor202 to oscillate and apply a torque on the shaft 203. FIG. 6 showsexemplary wave forms of the circuit 300. The coils can be alternativelyenergized in pairs via a half-wave electrical rectifier circuits tooscillate the rotor 202. Waveform 502 is a alternating current pulse,for example 60 Hz, at point 302 of the circuit 302. The coils 220 and224 are connected to an output of a first half-wave rectifier. Thevoltage waveform at 304, supplied to the coils 220 and 224, is shown aswaveform 504. The coils 222 and 226 are connected to an output of asecond half-wave rectifier. The voltage waveform at 306, supplied to thecoils 222 and 226, is shown as waveform 506. In this way, the coils arealternately provided a same polarity to induce oscillations as discussedabove. Also, the frequency can be varied by a Variable-Frequency (VF)controller such as via pulse width modulation. Variation in vibrationfrequency may provide an advantage to adjust the vibration for the sizeof the ballast. For example, more tightly packed ballast may by tampedbetter by applying higher frequency vibrations. The coil oscillator canbe easily adjusted, for example, by an operator with a simple adjustmentto the controller. By increasing the current and voltage a high torque(for example on the order of 1500-2000 Nm) can be achieved. It will beappreciated that the sinusoidal waveforms shown in the drawings areexemplary and other waveforms (square waves, triangle waves, etc) mayalso be used.

A controller 310 may also receive location information from a sensor(e.g., a solid state position sensor, a hall effect sensor, etc) 228.The controller 310 may use this information to control the frequency ofthe oscillations and also the resting location of the rotor 202. Thecontroller may adjust the amplitude of the positive and negative signalssupplied to the circuit 300 to balance the rotor 202 at a desired offsetangle. Preferably, the offset angle is 5 degrees. It will be appreciatedthat an exemplary benefit of including a coil on the rotor 202 andproviding the offset position is that a position sensor is notnecessary. Thus, costs and complexity in the controller may be reduced.

By using coil-oscillator vibrator unit, a vibrating workhead may achievecontrol of the vibration frequency. For example, the vibration frequencycan be adjusted to suit ballast conditions. The reduction in contactingparts can improve the wear of the oscillating vibrator. Exemplaryadvantages of the disclosed coil-oscillator are the provision of aconsistent desirable frequency (e.g., 50-60 Hz), less moving parts,reduction or avoidance of fluid leaks, reduction or elimination ofmechanical losses, reduction in size and weight and high reliability.The forces of the coil oscillator may also be more balanced providing animprovement in mechanical wear as compared to an electrically orhydraulically driven eccentric drive with an offset weight.

It will also be appreciated that this disclosure is not limited to railvehicles that perform tamping operations. For example, any railoperation that can benefit from oscillatory actuation can also realizeadvantages of the present disclosure. It will further be appreciatesthat this disclosure is not limited to rail vehicles and the disclosedvibration unit may be used in any application, for example, it may beused to provide lateral oscillations in a track stabilizer. It may alsobe used to provide vertical oscillation in a ballast compactor. It mayalso be used in other, non rail, application such as constructionequipment like gravel packers, jack hammers, and so forth.

The breadth and scope of the present disclosure should not be limited byany of the above-described exemplary embodiments, but should be definedonly in accordance with the following claims and their equivalents.Moreover, the above advantages and features are provided in describedembodiments, but shall not limit the application of the claims toprocesses and structures accomplishing any or all of the aboveadvantages.

Additionally, the section headings herein are provided for consistencywith the suggestions under 37 CFR 1.77 or otherwise to provideorganizational cues. These headings shall not limit or characterize theinvention(s) set out in any claims that may issue from this disclosure.Further, a description of a technology in the “Background” is not to beconstrued as an admission that technology is prior art to anyinvention(s) in this disclosure. Neither is the “Brief Summary” to beconsidered as a characterization of the invention(s) set forth in theclaims found herein. Furthermore, any reference in this disclosure to“invention” in the singular should not be used to argue that there isonly a single point of novelty claimed in this disclosure. Multipleinventions may be set forth according to the limitations of the multipleclaims associated with this disclosure, and the claims accordinglydefine the invention(s), and their equivalents, that are protectedthereby. In all instances, the scope of the claims shall be consideredon their own merits in light of the specification, but should not beconstrained by the headings set forth herein.

What is claimed is:
 1. A method for performing rail maintenance,comprising: providing a rail vehicle frame having wheels that travelalong rails, a workhead, and a vibrating unit coupled to the workhead,wherein the vibrating unit includes a rotor, a stator, a first rotorcoil and a second rotor coil coupled to the rotor and a first statorcoil and a second stator coil coupled to the stator, and further whereinthe first rotor coil is disposed at a first side of a shaft coupled tothe rotor, the second rotor coil is disposed at a second, opposing sideof the shaft, the first rotor coil is disposed proximal to the firststator coil, and the second rotor coil is disposed proximal to thesecond stator coil; and using the vibrating unit to impart vibration tothe workhead.
 2. The method of claim 1, further comprising coupling aflexible conductor between the first rotor coil and the first statorcoil.
 3. The method of claim 1, further comprising alternatingly causingthe first rotor coil and the first stator coil to have a same polarityand the second rotor coil and the second stator coil to have a samepolarity.
 4. The method of claim 1, further comprising alternatinglycausing the first rotor coil and the first stator coil to have oppositepolarity and the second rotor coil and the second stator coil to haveopposite polarity.
 5. The method of claim 1, further comprising varyingat least one of a frequency, voltage and current supplied to at leastone of the first rotor coil, the second rotor coil, the first statorcoil and the second stator coil.
 6. The method of claim 1, using theworkhead to perform tamping operations.
 7. A method, comprising:providing a vibration unit having a rotor, a stator, a first rotor coilcoupled to the rotor, a second rotor coil coupled to the rotor, a firststator coil coupled to the stator and proximal to the first rotor coil,and a second stator coil coupled to the stator and proximal to thesecond rotor coil; and alternatingly causing the first rotor coil andthe first stator coil to have a first state and the second rotor coiland the second stator coil to have a second state.
 8. The method ofclaim 7, further comprising causing the first rotor coil and the firststator coil to have the second state when the second rotor coil and thesecond stator coil have the first state.
 9. The method of claim 7,further comprising coupling a first flexible conductor between the firstrotor coil and the first stator coil, and coupling a second flexibleconductor between the second rotor coil and the second stator coil. 10.The method of claim 7, further comprising varying at least one of afrequency, voltage and current supplied to at least one of the firstrotor coil, the second rotor coil, the first stator coil and the secondstator coil.